Conventional motovibrators are essentially constituted by an electric motor in which the stator is accommodated within a casing and the rotor rotates integrally with a shaft that is coupled to one or more eccentric masses, the rotation of which generates controlled vibrations which are transmitted to the follower element of a machine in which the motovibrator is integrated. In particular, motovibrators are known which are provided with a shaft that passes through the rotor on the stator and are coupled at the opposite ends to respective eccentric masses.
For some applications, typically linked to the screening of materials, it is required to be able to modify the relative angular position of the eccentric masses keyed to the ends of the shaft in order to be able to modify consequently the spatial distribution of the vibrations transmitted to the follower element to which the motovibrator is applied.
In order to achieve this functionality, solutions are known in which at least one of the eccentric masses is “clamped” to the rotating shaft, with the possibility of continuous adjustment of its angular position around the rotation axis of said shaft, or which allow the possibility to apply additional secondary masses in predefined angular positions on a main eccentric mass.
Both of these solutions require the manual intervention of a specialized operator who, when the machine is not moving, intervenes manually to modify the angular position of the eccentric mass with respect to the rotation axis of the shaft or to apply or remove the additional secondary masses to/from the main eccentric mass or move them to a different angular position. After each adjustment it is necessary to restart the machine and check that the operation is the desired one; if it is not, the adjustment must be repeated by proceeding by successive attempts.
These solutions of the known type are not free from drawbacks, which include the fact that in order to perform the adjustment of the angular offset of the eccentric masses arranged at the mutually opposite ends of the rotating shaft it is necessary to stop the machine in which the motovibrator is incorporated, interrupting its production process, with consequent inefficiencies and increase in production costs.
Besides, the need to proceed by successive attempts further increases the execution times of these adjustment interventions, worsening the inefficiencies mentioned above.
It is also noted that an adjustment intervention performed by successive attempts is always approximate, particularly in the case of motovibrators with additional secondary masses on the eccentric masses which can be only moved to predetermined positions.
Moreover, these known solutions, by not allowing the execution of “dynamic” adjustments, in real time and continuous, force the machines in which they are incorporated to operate in conditions which are sometimes not optimum, until a new adjustment is performed, penalizing their performance.
Furthermore, the execution of these adjustment interventions entails the use of specialized and expert labor in view of the delicate nature of the operations to be performed.